Composition for use in a dishwashing machine

ABSTRACT

Composition for use in a water tank in the kitchen or sanitary sectors characterized by a basic composition essentially evolving its function following addition to a first water filling of the water tank, in the form of a tablet and at least one particle, with at least one core, which comprises at least one substance evolving its function essentially following an at least partial emptying of the first water filling from the water tank Ad and the inflow of fresh water and a covering substantially completely surrounding the core or cores comprising at least one compound, whose solubility increases with decreasing concentration of a specific ion in the surrounding medium, the at least one particle being so arranged in or on the tablet that the surface of the particle or particles is at most only partly in direct contact with the surface of the basic composition surrounding the same and the concentration of the specific ion in the local environment of the particle or particles is sufficiently high up to a substantially complete dissolving of the tablet in order to prevent a substantial dissolving of the covering or a substantial detachment of the covering from the core or cores.

The present invention relates to a composition for use in a dishwashingmachine and a process for the use thereof.

Although modern dishwashing machines in most cases have numerousdifferent washing programs, which differ with regards to the durationand temperature of the individual washing cycles, all washing programsessentially consist of the following basic steps: preliminary washingcycle, main cleaning cycle, one or more intermediate rinsing cycles, aclear rinsing cycle and drying. Whereas the machine dishwashing agentfor bringing about the cleaning action is added at the start of the maincleaning cycle, during the clear rinsing an cycle special agents areused, e.g. clear rinsing agents. Clear rinsing agents are intended toensure that when washing with water water droplets are not left behindon the washed articles which, after drying on, leave behind marks ofsubstances dissolved/dispersed in the droplets.

These two functionalities, namely the cleaning action of the machinedishwashing agent and the described function of a clear rinsing agent,have hitherto been brought about using two separate charging or dosingdevices and products charged or dosed at different points during thedishwashing cycle.

Apart from the use of clear rinsing agents, there is still a need forfurther substances evolving their activity during the washing or rinsingcycle, such as e.g. an antibacterial activity (e.g. cationic compoundsor triclosan), silver protection agents (e.g. benzotriazole), an odorousaction (fragrances, perfume), bleaching action/disinfection (chlorinebleaches), odour masking (e.g. polyvinylpyrrolidone), anti-coatingagents and enzymes for additional purposes (e.g. lipase for removinggrease and fat deposits in the dishwasher). However, modern dishwashershave no suitable charging systems for this purpose.

The aim of the present invention was consequently to combine in a singlefunction the cleaning function and the function or functions of thesubstance or substances to be added during the clear rinsing cycle witha constant efficiency compared with the results obtainable with aseparate charging or to permit the charging of substances other than theclear rinsing agent in the clear rinsing cycle.

DE-OS 20 65 153 and 20 07 413 disclose detergent blanks for use asdetergents, in which it is inter alia provided that two componentshaving a different functionality are combined. The structure comprisesan enveloping shell, which is e.g. formed from two shell halvescomprising a cleaning agent, as well as a cavity enclosed by the shellsand which contains additives such as softeners, brighteners, etc.

British patent 1 390 503 discloses a liquid detergent containingcapsules, which are insoluble in the composition, but release theircontent if the composition is diluted with water. This objective isachieved in that the capsules are coated with a substance having a poorsolubility in water solutions with high ionic strength, but becomingsoluble if the ionic strength is reduced by dilution. It is pointed outthat this procedure can be used to incorporate materials in the liquidcleaning agent, which are unstable in the latter or would produce aninstability if added directly. It is also proposed that this procedurebe used in order to delay the release of a specific substance. Referenceis made to use in machine dishwashing agents and it is proposed for theencapsulation of tribromosalicylanilide in order to stabilize thelatter. The encapsulated material is released within two minutesfollowing the dilution of the cleaning agent with water, i.e. in themain cleaning cycle.

U.S. Pat. No. 4,082,678 describes a fabric conditioning productcomprising a closed container containing a releasable agent, which isused to make water-insoluble or non-dispersible an inner containerlocated in the container and which is normally water-soluble orwater-dispersible, the inner container is containing a fabricconditioner. The inner container is made from a substance, whosesolubility in water is highly dependent on the ionic strength or thepH-value of the medium and the agent used for rendering the innercontainer insoluble is an agent for controlling the pH-value or ionicstrength.

Japanese patent applications KOKAI 60-141705, 61-28440, 61-28441,61-28596, 61-28597 and 61-28598 describe processes for the production ofpH-sensitive microcapsules for use in detergents. The pH-sensitivecoating is a copolymer of the following monomers:

A) at least one basic monomer of formula I:

in which R is hydrogen or a methyl group, R¹ and R² in each case analkyl group with 1 to 3 carbon atoms and x an integer from 1 to 4, B) atleast one monomer, which is insoluble or difficultly soluble in waterand

C) at least one water-soluble monomer.

It is stated that the polymers described are insoluble at a pH-value of9.5 or higher and are soluble at a pH-value of 8.5 or lower. Adescription is given of different ingredients of cleaning agentcompositions, which can be successfully and usefully coated with thepolymers described. The aim of the invention described therein is thatthe substances only evolve their function during the rinsing cycle,protect the same up to the start thereof and then immediately releaseit. The use for dishwashing machines is not described.

A disadvantage of the solution described in these Japanese patentapplications is that the enveloped particles are in direct contact withnon-alkaline washing water at the start of the washing cycle which canlead to a partial dissolving of the protective envelope.

Japanese patent KOKAI 50-77406 discloses a washing aid surrounded by awater-soluble envelope obtained by mixing polyvinyl acetal dialkylaminoacetate and at least one organic acid, which is solid at ambienttemperature. This protective envelope serves to protect the washing aidduring the main washing cycle and release it during rinsing cycles. Thedescribed compound reacts to a change of the pH-value between the mainwashing cycle and the rinsing cycle. The correspondingly envelopedparticles are mixed with conventional pulverulent detergent. Here againthe disadvantage of a possible partial dissolving of the protectiveenvelope at the start of the washing cycle occurs.

European patent applications EP 284 191 A2 and 284 334 A2 disclose awater-soluble polymer film for the release of washing additives in therinsing cycle of washing machines which, during the normal washingcycle, remains intact over a typical temperature range and rapidlydissolves in the rinsing cycle. It is pointed out that although the useof pH-sensitive coatings is known, said films are normallytemperature-sensitive, so that they are not reliably stable during thedifferent temperatures occurring in the washing cycle. The solutionproposed is a pH-dependent material (which undesirably also has apositive temperature-dependent dissolving behaviour), which is combinedwith a material having a negative temperature-dependent dissolvingbehaviour. This combination is intended to guarantee that the coatingsdo not dissolve at the high temperatures at the start of the washingcycle (particularly the very high temperatures occurring in Americanmachines). No reference is made to a use for machine dishwashing agents.

European patent application EP 481 547 A1 discloses multilayer machinedishwashing agent tablets with a core, a separating layer surroundingthe core and an outer layer for the sequential release of theingredients of the different layers. The aim of this tablet is to solvetwo different problems, namely 1) incompatible materials can beformulated together in a single tablet and released at different timesin order to prevent mutual influencing and 2) compositions intended toevolve their functions at different times can be formulated in a singletablet.

An important disadvantage of this prior art is that for initiating thedissolving of the enveloping layer the temperature and/or in particularthe contact time with the washing solution is used as the initiatingfactor, i.e. temperature-sensitive materials are used for the envelopematerial. As the temperature/time gradient in dishwashing machines canvary very widely as a function of the selected program, it is difficult,if not impossible, to select a material for the envelope which is usablefor all possible programs of modern dishwashing machines. EP 481 547 A1(p 7, lines 37 to 43) admits that the choice of the material of theenveloping layer must take account of equipment and program-specificdetails. Thus, the practical usability of the described products issignificantly limited.

PCT application WO 95/29982 discloses a machine dishwashing agent with adelayed release of a clear rinsing agent in the form of a nonionicsurfactant, which forms together with an inorganic builder salt a coreparticle, which is provided with a wax-like envelope in order to ensurethe delayed release This envelope is a substance which does not melt atthe operating temperatures encountered in the cleaning cycle, but whichso gradually chemically disintegrates under alkaline pH-values thatthere is still left at the end of the main cleaning cycle an activeclear rinsing agent quantity which is transferred into the clear rinsingcycle.

It is disadvantageous that the envelope is rendered soluble by chemicalsaponification under alkaline pH-values, so that the time at which theclear rinsing substance is released from the core is a function both ofthe temperature and the length of the main cleaning cycle. The patentapplication provides no teaching for the formulation of a product withwhich it is possible to release the clear rinsing agent only when theclear rinsing cycle arrives in all washing programs of any machine type.In addition, the core ingredient active as the clear rinsing agent is anonionic surfactant, which is absorbed on an inorganic builder salt.This leads to inferior clear rinsing results, particularly with respectto marks on glass. The product is finally a mixture of granulardetergent and granular clear rinsing agent particles.

In view of the prior art, the problem of the present invention is toprovide a composition usable for most rinsing/washing programs ofdifferent dishwashing machine types and in each of these cases thesubstance or substances having only to evolve their action in the clearrinsing cycle are only released at the earliest at the start of theclear rinsing cycle. The aim is to achieve this without restricting thechoice of the cleaning agents used, the substance or substances used forthe clear rinsing cycle and other ingredients of the composition.

According to the invention this problem is solved with a solutioncharacterized by a basic composition evolving its function essentiallyin the main cleaning cycle of the dishwashing machine; as well as atleast one particle, with at least one core incorporating at least onesubstance, which evolves its function essentially in the clear rinsingcycle of the dishwashing machine and an envelope substantiallycompletely surrounding the core or cores incorporating at least onecompound, whose solubility increases with decreasing concentration of aspecific compound in the surrounding medium. Agents are provided so thatat the start of the clear rinsing cycle a significant dissolving of theenvelope or a significant detachment of the envelope from the core orcores is prevented.

In an advantageous embodiment the concentration of the specific compoundin the local environment of the particle or particles is sufficientlyhigh up to the start of the clear rinsing cycle so that up to this timethere is no significant dissolving of the envelope or significantdetachment of the envelope from the core or cores.

Preferably the particle or particles are coated with a substance which,substantially independently of the concentration of the specificcompound in the surrounding medium, dissolves or separates during themain rinsing cycle of the dishwashing machine.

The basic composition is preferably in the form of a tablet.

An embodiment of the invention proposes that the at least one particleis so placed in or on the tablet that the concentration of the specificcompound in the local environment of the particle or particles issufficiently high up to the complete dissolving of the tablet to preventa significant dissolving of the envelope or a significant detachment ofthe envelope from the core or cores.

Preferably the particle or all the particles are received in at leastone tablet cavity completely surrounded by the basic composition.

The at least one cavity can receive one or more particles having aloneor together essentially the same volume as the cavity.

Preferably the at least one cavity has a larger volume than the or allthe particles received in the particular cavity.

In an alternative of the invention the particle or particles arearranged loosely in the cavity interior.

In another alternative the particle or particles are fixed, preferablyby an adhesive, in the cavity interior.

In a further embodiment the cavity is positioned substantially centrallyin the tablet interior.

The invention also proposes that the tablet has a single, substantiallyspherical cavity.

According to the invention the cavity receives a single, substantiallyspherical particle, whose external diameter is smaller than the internaldiameter of the cavity.

According to another embodiment the or all the particles are received inat least one cavity of the tablet, which is only partly surrounded bythe basic composition.

Preferably the cavity is a depression in one of the surfaces of thetablet in which the particle or particles are at least partly received.

In a preferred embodiment the particle is so received in the cavity ordepression that it does not project over the surface or surfaces of thetablet.

A special embodiment of the invention proposes that the cavity ordepression only contains a single particle, whose volume and shape inthe vicinity of the cavity or depression substantially coincides withthe volume and shape of the cavity or depression and substantiallycompletely fills the same.

Preferably the cavity or depression is parallel to one of the surfacesto which it opens or in which it is located and has a substantiallycircular cross-sectional surface.

The invention also proposes that the cavity or depression opens to thesurface or surfaces only to the extent that the particle or particlesreceived therein cannot pass through the opening or openings of thecavity or depression.

It is inventively preferred for the particle or particles to be looselyarranged in the cavity or depression.

In a further alternative the particle or particles are fixed in thecavity or depression, preferably by an adhesive.

According to an embodiment of the invention the basic compositionincorporates at least one composition chosen from the group comprisingmachine dishwashing agent composition, water softener composition andwashing intensifier composition.

In a preferred embodiment of the invention the envelope incorporates atleast one compound which for the concentration of the specific compoundat the end of the main cleaning cycle of the dishwashing machine is notor is only slightly soluble and at the concentration of the specificcompound in the clear rinsing cycle has such an adequate solubility thatin the clear rinsing cycle it is so substantially dissolved or detachedfrom the core or cores that an at least partial escape of the corematerial into the clear rinsing cycle medium is possible.

Preferably the solubility of the compound increases with decreasing OH⁻ionic concentration and therefore decreasing pH-value in the surroundingmedium.

In particularly preferred manner the compound at a pH-value above 10 haslittle or no solubility and at a pH-value below 9 has an adequatesolubility to ensure a substantially complete dissolving or detachmentfrom the core or cores in the clear rinsing cycle, so that an at leastpartial escape of the core material into the clear rinsing cycle mediumis possible.

Preferably the compound incorporates a polymer, preferably apH-sensitive polymer, which comprises at least one repeat unit, whichhas at least one basic function, which is not part of the polymerbackbone chain.

In a preferred embodiment the polymer comprises at least one repeatunit, which is based on a compound selected from the group comprisingvinyl alcohol derivatives, acrylates or alkyl acrylates, which have saidbasic function.

According to the invention the polymer is a carbohydrate functionalizedwith said basic function.

The aforementioned basic function is preferably an amine and inparticularly preferred form a secondary or tertiary amine.

In a preferred alternative the repeat unit is based on a compound withthe following formula III:

in which G is a linking group selected from —COO—, —OCO—, —CONH—, NHCO—,—NHCONH—, —NHCOO—, —OCONH—or —OCOO—, R₁, independently of one another,is hydrogen or an alkyl group with 1 to 3 carbon atoms, R₂ independentlyof one another, hydrogen or an alkyl group with 1 to 5 carbon atoms andx is an integer from 1 to 6.

Preferably the repeat unit is based on a compound with the followingformula IV:

in which R₁, independently of one another, is hydrogen or an alkyl groupwith 1 to 3 carbon atoms, R₂, independently of one another, is hydrogenor an alkyl group with 1 to 5 carbon atoms and x is an integer from 1 to6.

In a further embodiment the basic function is an imine or a basic,aromatic N-containing group, preferably a pyridine group or an imidazolegroup.

In a further embodiment the pH-sensitive polymer is derived fromchitosan.

The invention finally proposes that the compound incorporatesK-carrageenan.

In a special embodiment of the invention the core or cores comprise atleast one material selected from the group constituted by surfactants,antibacterial compositions, silver protection agents, fragrances,bleaches, disinfectants, odour masking agents, anti-coating agents andenzymes.

The core or at least part of the cores can be in the form of anencapsulated liquid, preferably in the form of a liquid contained in agelatin capsule.

According to a further embodiment the core or at least part of the coresis in solid form.

Preferably the core or at least part of the cores has a melting point ofmore than 35° C., preferably between 55 and 70° C.

The invention also relates to a process for performing a dishwashingcycle in a dishwashing machine, where the composition according to theinvention is added at an appropriate time during the prerinsing cycle ormain cleaning cycle to the medium in the dishwashing machine.

In a special embodiment of the invention for the case that the basiccomposition in the form of a tablet is not able, following itsdissolving in the medium up to the end of the main cleaning cycle tomake available a concentration of the specific compound in the mediumwhich is sufficiently high in order to prevent a significant dissolvingof the envelope and a significant detachment of the envelope from thecore or cores, said adequate concentration of the specific compound ismade available by adding a further composition such as e.g. a machinedishwashing agent composition, to the medium of the main cleaning cycleat an appropriate time.

The composition according to the invention is characterized in that itgives excellent results both in the main cleaning cycle and in the clearrinsing cycle of a dishwashing machine. The basic composition, e.g. inthe form of a tablet, is dissolved during the main cleaning cycle andcan evolve its corresponding action (cleaning, water softening, washingintensification, etc.). The particle according to the invention containsas the core material the substance or substances evolving their mainfunction in the clear rinsing cycle of the dishwashing machine, e.g.clear rinsing agents.

Said substance or substances are protected by an envelope which, at theconcentration of a specific compound, e.g. a specific ion such as OH—ion (and therefore at a specific pH-value) and the temperature of themain cleaning cycle are stable and do not or only insignificantlydissolve or separate. Only when said concentration drops significantlyby dilution, i.e. at the start of the clear rinsing cycle, is thesolubility of the enveloping material reduced so significantly that itrapidly dissolves or separates and that the active core material isreleased in the surrounding medium. It is important that the protectionof the core material acts from the addition of the inventive compositionto the water up to the start of the clear rinsing cycle, i.e. before thecleaning liquor reaches a sufficiently high concentration of thespecific compound, as will be explained hereinafter.

As an alternative to the tablet form of the basic composition used inpreferred manner, other administration forms are possible and arecovered by the protective scope of the invention. Thus, the particleswith the envelope changing in the case of a modification of theconcentration of the specific compound with respect to its solubilitycan be connected, e.g. enveloped with the basic composition by agranulation or similar process. In order to ensure for this embodimentan optionally desired, reduced contact between the envelope and thebasic composition, the particles can be surrounded by a furtherprotective jacket, which e.g. comprises a water-soluble compoundindependent of the concentration of the specific compound. With thisembodiment during the main cleaning cycle initially the basiccomposition and protective jacket of the particles are dissolved andonce again the particles protected by the inventive envelope are leftbehind.

Unless special charging or dosing aids are used for charging or dosing,which can retain the particles according to the invention, saidparticles must be chosen sufficiently large that they do not getdischarged to a significant extent during the pumping out following themain cleaning cycle and intermediate rinsing cycle or cycles from thedishwashing machine.

The invention is now described in greater detail by means of thefollowing examples and drawings, wherein show:

FIG. 1 A typical pH-profile of a dishwashing machine. FIG. 2 A firstembodiment of the inventive composition in cross-section. FIG. 3 Asecond embodiment of the inventive composition in cross-section. FIG. 4A third embodiment of the inventive composition in cross-section. FIGS.5a and b A fourth embodiment of the inventive composition incross-section and in plan view. FIG. 6 A fifth embodiment of theinventive composition in cross-section.

The ionic concentration or pH-profiles of the cleaning or rinsing mediumin a dishwashing machine are dependent on the ingredients of thecleaning or rinsing agent used. A typical pH-profile when using aconventional, basic machine dishwashing agent, e.g. CALGONIT® can begathered from FIG. 1 (dishwashing machine used, BOSCH model SMS 3047).

The vertical, broken line subdivision indicates the duration of thefollowing stages: prerinsing, main cleaning, intermediate rinsing, clearrinsing. It is clear that the pH-value during most of the main cleaningcycle is between 10 and 10.5. The pH-value drops following the pumpingout of the washing liquor at the end of the main cleaning cycle and theinflow of fresh water to a value of 9 during intermediate rinsing and tobetween 8.5 and 9 during clear rinsing.

FIGS. 2 to 6 reveal possible embodiments of the composition according tothe invention. In all cases the preferred tablet form is chosen forillustration.

FIG. 2 shows a tablet 1 comprising two half-tablets 2 and 3, which canhave the same or a different composition. For example it is possible touse a conventional, commercially marketed two-layer tablet, in which thetwo layers normally have a different composition and have differentcolours.

Roughly centrally in both half-tablets is provided a roughlyhemispherical recess 4 or 5 which, when the tablet 1 is joined together,form a roughly spherical cavity.

In the represented embodiment in said cavity is placed a single particle6 comprising a core 8 and the envelope 9 and its external diameter isslightly smaller than the internal diameter of the tablet cavity. Inanother embodiment of the invention particles 6 can also completely fillthe complete tablet cavity and engage against the walls thereof. If theinternal diameter of the cavity is slightly larger than the externaldiameter of the particles 6, the particle can either be loosely receivedin the cavity or fixed therein by an adhesive applied.

In the embodiment where contact between the particle and the surroundingbasic composition is to be reduced or completely prevented, theadditional advantage arises that during the production process, e.g. themoulding of the individual components in successive stages, adeformation and possibly resulting damage to the core or cores and/orenvelope of the core is reliably avoided and which could lead to areduction in the protective action of the core envelope. By preventingany pressure on the particle during any production process phase, it canreliably also be prevented that for a specific core composition there isno “bleeding” thereof into the material of the envelope and the basiccomposition. Finally, for specific compositions of the envelope 9 andbasic composition 2, 3, it can be advantageous to avoid an intimate,full-surface contact, because otherwise undesired reactions could arisein the boundary layers.

According to a preferred embodiment of the invention, the surface of theparticle is at the most only in partial direct contact with the surfaceof the basic tablet composition surrounding it. This can take place inthe manner described in the application, but also in other waysachieving the sought objective. Examples are the loose arrangement of asmaller particle in a larger cavity, the fixing of a smaller particle inthe larger cavity in such a way that no or only a partial contact occursbetween the particle and the basic composition, the application of aprotective coating to the core envelope according to the invention, etc.

The term “local environment”, as used in conjunction with a specialembodiment of the particle according to the invention, designates theimmediate environment around said particle. The concentration of thespecific compound in this local environment of the particle is thedetermining factor for its stability. For the preferred embodiments intablet form this concentration in the local environment of the particleat least up to a substantially complete dissolving of the tablet isdetermined by the molecule,passing into solution. Preferably the originof the “specific compound”, at least in the initial phase of the maincleaning process, is a compound from the basic composition forming thetablet or is produced by it in the surrounding medium. In the mosttypical case with conventional, basic dishwashing agents, it isrepresented by OH⁻ ions, whose concentration can be expressed as apH-value.

If e.g. a basic machine dishwashing agent composition is not used as thebasic composition and instead e.g. a water softener composition or awashing intensifier composition, the protection of the particle envelopeis possibly only ensured by an adequately high concentration of thespecific compound in the local environment of the particle until thebasic composition, e.g. the tablet has completely dissolved, namely inthe cases where the basic composition is not able to provide asufficiently high, corresponding concentration in the washing liquor. Inthese cases the sufficiently high concentration in the washing liquor(and therefore also in the local environment of the particle orparticles) is brought about by dissolving the machine dishwashing agent(or a further specific additive).

Obviously not only a conventional adhesive can be used for fixing theparticle in the cavity and instead other compositions and agents can beemployed which fulfil the same purpose, e.g. a mechanical fixing, suchas e.g. adequate frictional engagement between tablet and particle at atleast certain points or a plug connection between tablet and particle.It is also possible to use further compounds which melt or dissolveduring the main cleaning cycle as fixing agents between the tablet andparticle. Obviously for the design of the cavity in the tablet or theparticle received therein the most varied further geometrical shapes arepossible, such as e.g. an ellipsoid, cylinder, etc. The design and sizeof the cavity in the tablet and the particle received therein need notcorrespond to one another. Thus, a cylindrical particle can e.g. bereceived in a spherical cavity. All possible further combinations cantake place within the scope of the present invention. It is alsopossible to fill the cavity with several smaller particles instead of asingle particle.

FIG. 3 shows a second embodiment of the inventive composition based on aconventional two-layer tablet 1. Here the upper half-tablet 3 is in twoparts, which make available both an adequate cavity 5 for receiving theparticle 6 and also an opening to the tablet side 11. Thus, in this casethe particle 6 is not completely surrounded by the basic composition ofthe tablet 1, so that it is visible from the outside in the interior ofthe tablet 1. Here again the particle can either be loosely received inthe cavity 5 (provided that by a corresponding choice of the size of theparticle 6 on the one hand and the size of the opening of the cavity 5to the tablet side 11 on the other it is ensured that the particle orparticles cannot pass through the opening in the cavity) or fixed in theinterior of the cavity by corresponding agents, such as e.g. adhesives.

FIG. 4 shows a third possible embodiment. It is based on a unitarytablet 1′, i.e. a single layer 2′ with a unitary composition and colour.Using a suitable device a depression 4′ is formed in said layer 2′. Intothe depression 4′ is placed the particle 6′, which in this case, becausethe depression to the side 11′ of the tablet 1 is only open to theextent that without fixing the particle could drop out of thedepression, it is fixed in the depression with an adhesive 10′ or afixing intermediate layer or mechanically (e.g. by frictionalengagement). This principle can obviously be transferred to multilayertablets.

Here again the most varied geometrical configurations are possible.Thus, is the depression e.g. parallel to the side 11′ can have asubstantially circular cross-section. However a random number of othercross-sections is possible, e.g. any random polygon. The particle 6′received in the depression 4′, as in the embodiment of FIG. 3, canassume any random shape (independent of the shape of the depression 4′),such as e.g. an ellipsoid, cylinder, parallelepiped, etc.

It is also possible to fix the particle 6′ in a cavity in the tabletopen on both sides, such as e.g. in a cylindrical hole 4′ passingthrough the tablet body 1′ and in which is fixed a corresponding,cylindrical particle 6′ having a core 8′ and an envelope 9′ (FIGS. 5aand b).

A further possible embodiment can be gathered from FIG. 6. This isessentially constructed like the embodiment of FIG. 4, i.e. a tablet. 1′having a unitary structure, i.e. formed from a single layer 2″ with aunitary composition and colour. However, in the present case theparticle 6″ not only contains a single core (as in FIG. 4), but aplurality of cores 8″ all embedded in an envelope 9″. In this embodimentit is e.g. also possible to incorporate into a particle 6″ cores havingdifferent composition and different shape (encapsulated material orsolid cores).

Both in the represented embodiments and further conceivable alternativesit is essential that for the particle containing the substance orsubstances to be released in the clear rinsing cycle, at least in thefirst phase of the main cleaning cycle, a local environment exists withan adequate concentration of the specific compound serving as a“trigger” for dissolving the envelope, i.e. in a phase where theconcentration is still relatively low, i.e. briefly in a range in whichincreased solubility of the envelope would exist. This ensures that theenvelope has an adequate stability up to the clear rinsing cycle.

EXAMPLE 1 Production of the Core

a. Core for a Particle for the Controlled Release of a Clear RinsingAgent in the Clear Rinsing Cycle

The core of the particle or particles, which is only to evolve itsactivity in the clear rinsing cycle, must incorporate at least onesubstance acting as a clear rinsing agent. Advantageously in the presentinvention, use is made of a slightly foaming, nonionic surfactant. Suchsurfactants are e.g. fatty alcohol ethoxylates, fatty alcoholethoxylate/propoxylates, ethoxylate/propoxylate polymers, such as e.g.the products of Synperonic® and Brij® range of ICI, the products fromthe Plurafac®, Pluronic® and Lutensol® range of BASF, the products fromthe Genapol® range of Clariant and the products from the Poly-tergent®range of Olin.

Other possible examples for such surfactants are alkyl polyglycosides,glucamides and alkyl pyrrolidones. It is obviously possible to use allother surfactants able to evolve the desired action as clear rinsingagents.

Most substances known for use as clear rinsing agents are liquids orwax-like solids. However, in the present invention, a decisive part isnot played by the aggregate state of the substance acting as the clearrinsing agent. If liquids are used they can be made available prior tothe application of the envelope as surfactant-containing capsules, suchas e.g. gelatin capsules or can be brought into an envelopable state byother appropriate measures. Solids can conventionally be directlyprovided with the envelope and the coating process may have to bematched to the corresponding substance.

For the purposes of the present invention melt mixtures have provedparticularly advantageous and supply solid surfactant particles with amelting point above 35° C., preferably between approximately 55 and 70°C.

The combinations given in table 1 of different polyethylene glycols withthe surfactants Synperonic® RA 30, a block ethylene oxide/propyleneoxide, bound to a C₁₃-C₁₅ alcohol (C₁₃/C₁₅O(EO)₆(PO)₃) were produced inthe form of melt mixtures as cylinders weighing approximately 0.25 g.Melting point determinations gave the values of table 1.

TABLE 1 RA PEG PEG PEG PEG 30 8000 10000 20000 350000 melting Code [%][%] [%] [%] [%] point [° C.] C1 30 70 58-63 C2 40 60 57-60 A30 50 5057-60 A31 60 40 54-58 A30 50 50 57-60 C3 60 40 57-60 C4 65 35 55-59 A3350 50 59-65 C17 60 40 58-63 C18 70 30 57-64 A34 50 50 59-65 C15 60 4058-66 C16 70 30 57-64

Although all combinations are fundamentally suitable, in particular the50:50 mixture A33 revealed an excellent stability and was easy tohandle, particularly with a view to the subsequent coating process. Allsamples dissolved rapidly in water, so that in each case an optimumactivity as a clear rinsing agent is ensured.

The invention is obviously in no way restricted to the combinationsgiven in exemplified form. As stated, it is possible to use in thepresent invention any type of surfactant usable as a clear rinsingagent.

b. Core for a Particle for the Controlled Release of a Fragrance in theClear Rinsing Cycle

Bleach-containing, i.e. oxidizing dishwashing agent compositionssignificantly limit the use possibilities of fragrances usable in suchcompositions. The controlled release of a fragrance in the clear rinsingcycle would allow a much greater flexibility when using fragrances.

For the controlled release of a fragrance or fragrance composition inthe clear rinsing cycle, it is possible to produce a core for acorresponding inventive particle, in that a mixture of 50 wt. % meltedpolyethylene glycol, e.g. PET 8000, 25 wt. % fragrance or fragrancecomposition and 25 wt. % diethyl phthalate are cooled in a mould inorder to form an e.g. spherical particle weighing e.g. 0.75 g.

c. Core for a Particle for the Controlled Release of an AntibacterialComposition in the Clear Rinsing Cycle

The use of an inventive particle with a core or several coresincorporating an antibacterial composition in a tablet for use in adishwasher would make available the possibility of simultaneouslyreleasing two different compositions in the clear rinsing cycle, namelythe antibacterial composition from the core or cores of the particleaccording to the invention and the clear rinsing agent from theconventional charging device of the dishwasher.

For such a particle a corresponding core is produced in that a mixtureof 100% melted benzalkonium chloride (Barquat® MS-100) is cooled in amould in order to produce an e.g. spherical particle weighing e.g. 0.64g.

d. Core for a Particle for Controlled Release of Enzymes in the ClearRinsing Cycle

As proteases, which are conventionally used in dishwashing agentcompositions, are proved to degrade lipases and therefore can reducetheir activity, it would be desirable to incorporate such lipases intothe core or cores of a particle according to the invention, so that thelipases would only be released in controlled form in the clear rinsingcycle, which could permit an optimum efficiency of these enzymes.

For this purpose 0.4 g of a granular, lipolytic enzyme (e.g. Lipolase®100T (Novo)) can be added to a hard gelatin capsule with an e.g.rounded, cylindrical shape, e.g. of the type used for medicaments.

EXAMPLE 2 Screening Process for Enveloping Materials

As stated hereinbefore it is vital for the present invention that thematerial for enveloping the particle core or cores incorporates thesubstances evolving their function essentially in the clear rinsingcycle of the dishwasher has a solubility dependent on the concentrationof a specific, selected ion. In this way the envelope is substantiallyinsoluble in the main cleaning cycle and is made soluble and is detachedfrom the particle if the concentration decreases during the intermediaterinsing cycle or cycles or the clear rinsing cycle.

It has been observed that the dilution resulting from the pumping out ofthe washing liquor and the inflow of fresh water during the differentrinsing cycles leads to the concentration decreasing 20 to 200 timesbetween the end of the main cleaning cycle and the last rinsing cycle.

On the basis of this observation processes for screening the suitabilityof different polymers for their use as enveloping materials have beendeveloped consisting of determining the solubility of such polymers attwo different concentrations, which differ by at least 20 times andpreferably by 200 times.

The values for the concentration, to be used during the screening of thepolymers, are dependent on the formulation of the basic composition ofthe tablet into which the enveloped particle is to be incorporated.

In fact, the value for the highest concentration to be used for thescreening process corresponds to the concentration of the selected ionencountered in the washing liquor, after the machine dishwashing agenthas completely ok dissolved. Once this concentration has beendetermined, the lower value for the concentration should be fixed at 20to 200 times below said higher value. With these details it falls withinthe routine capacity of an expert in this field to determine the valuesfor the concentration of the test solutions to be used in the differenttest methods described hereinafter.

Process for the Preparation of the Test Solution and Performing andEvaluating the Test

The materials to be investigated are dissolved in solvents in which theyare readily soluble. The solutions are spread over glass plates, thendried at ambient temperature until a constant weight occurs.

The glass plates are added at a controlled temperature to a beaker withtest solution. The solution is then stirred with a magnetic stirrer at acontrolled stirring speed. After about 10 minutes the glass plates areremoved from the beaker and dried at ambient temperature to constantweight. The results are expressed as weight loss (%).

Obviously the screening processes must be adapted to the composition ofthe machine dishwashing agent, because they exert a significantinfluence on the concentration or pH-profile in the dishwashing cycle.The aim is in each case to check the degree of solubility of thecorresponding materials under different states, namely high or lowconcentration or pH-value.

With this information an average capacity only is required on the partof the expert to draw up specific test parameters for screening. Forexample, hereinafter two screening processes are described enabling thetesting of some of the possible materials for the envelope of theparticle according to the invention.

Screening Process 1

Screening process 1 was performed with buffer solutions as the mediumfor simulating the washing liquor. To this end two buffer solutions wereprepared in the following way:

Stock solution: 7.507 g glycine buffer (Merck 104169) 5.850 g NaCltopped up with water to 1000 ml pH 8 buffer 500 ml stock solutionsolution: 500 ml distilled H₂O 1.23 g of 1 N NaOH pH 10 buffer 500 mlstock solution solution: 500 ml distilled H₂O 32.6 g of 1 N NaOH.

Screening Process 2

Screening process 2 was performed with the following cleaning agentformulation in order to simulate the conditions in different stages of adishwasher cycle. Concentrations of 4 to 5 g/l are of a conventionalnature for the cleaning agent load in the washing cycle. Concentrationsof approximately 20 to 40 mg/l are of a conventional nature for theclear rinsing cycle.

Cleaning agent formulation Ingredient wt. % Sodium perborate monohydrate9.00 Sodium tripolyphosphate 48.00 Sodium carbonate 28.00 Polyethyleneglycol 4.00 Polymer 1.50 TAED 3.00 Enzyme 1.50 Surfactant 3.50 Additive1.50 Total 100.00

Screening Process 3

Screening process 3 is used for screening compounds, whose solubilitychanges as a function of the concentration of potassium ions. Thecompounds discovered with such a screening process can be used if in themain cleaning cycle, as stated hereinbefore, there is a correspondinglyhigh potassium ion concentration, which must be correspondingly reducedby dilution in the clear rinsing cycle.

Screening process 3 was performed with the following formulation tosimulate corresponding conditions.

Formulation Ingredient wt. % Potassium tripolyphosphate 13.6 Potassiumbicarbonate 34.0 Potassium sulphate 23.1 Potassium chloride 12.4Potassium carbonate 9.7 Boric acid 2.0 Sodium perborate monohydrate 2.0TAED 1.0 Paraffin 1.0 Protease 0.2

Example 3 Selection of Materials for the Particle Envelope

Using the screening processes described in example 2 different materialswere tested for their suitability as an envelope for the particleaccording to the present invention. One of these materials, hereinaftercalled “polymer 1” is a polymer such as is described in Japanese patentapplication KOKAI 61-28440, i.e. having the general formula II with1/(1+m+n)=0.35; m/(1+m+n)=1500-1800.

The polymer was produced in the conventional manner by bulkpolymerization. The screening test results were as follows:

Screening Process 1

Films of polymer 1 were produced from a 10% solution in isopropanol.

pH-value of weight loss at 30° C. weight loss at 60° C. buffer solution[%] [%] 10 7-8 5-8 8 81-88 91-95

Screening Process 2

Films of polymer 1 were produced from a 10% solution in a mixture ofwater and 1 N HCl (17:1).

Detergent conc. Weight loss at 30° C. Weight loss at 60° C. pH-value [%][%]   4 g/l  8-15  6-15 10.6 0.02 g/l 90-95 89-95  8.5

The invention is obviously not restricted to this exemplified polymerand naturally a wide variation possibility exists with respect to thepolymers referred to in Japanese patent applications KOKAI 60-141705,61-28440, 61-28441, 61-28596, 61-28597 and 61-28598 and can be extendedto compounds of formula IV:

in which R₁, independently of one another, is hydrogen or an alkyl groupwith 1 to 3 carbon atoms, R₂, independently of one another, is hydrogenor an alkyl group with 1 to 5 carbon atoms and x is an integer from 1 to6.

In addition, within the larger class of compounds according to formulaIII:

in which G is a linking group selected from —COO—, —OCO—, —CONH—, NHCO—,—NHCONH—, —NHCOO—, —OCONH—or —OCCOO—, R₁, independently of one another,is hydrogen or an alkyl group with 1 to 5 carbon atoms and x is aninteger from 1 to 6, in exemplified manner polymers can be used having arepeat unit based on a compound of formula V:

e.g. a pH-sensitive polymer (“polymer 2”) with the repeat unit VI, whichis commercially obtainable from SANKYO under the trade name AE®,

The above-described screening process 2 was also carried out withpolymer 2. 15 g of polymer 2 and 5 g of Mowiol® 3-98 (Clariant) weredissolved in 200 ml of a water/ethanol/1 N HCl 12:8:1 mixture. Filmswere formed and tested in the manner described hereinbefore and thefollowing results were obtained.

Detergent conc. Weight loss at 30° C. Weight loss at 60° C. pH-value [%][%]   4 g/l 2-8 5-7 10.6 0.02 g/l 32-40 45-47  8.5

Further polymers having the desired characteristics or which can beeasily modified in such a way that they are suitable for the purposes ofthe present invention are polymers of isomers or derivatives ofpyridine. preferably copolymers with styrene or acrylonitrile offormulas VII and VIII, in which G is a substituent at a random point ofthe pyridine ring.

A polymer according to formula VIII, namely poly(4-vinylpyridinestyrene) copolymer (Scientific Polymer Products, Inc.) “polymer 3” wastested according to screening process 2. 10 g of polymer 3 weredissolved in 230 ml of water/1 N HCl 6.25:1. The formation of the filmsand the performance of the tests were in the manner describedhereinbefore and the following results were obtained:

Detergent conc. Weight loss at 30° C. Weight loss at 60° C. pH-value [%][%]   4 g/l 0-6  5-12 10.6 0.02 g/l 68-85 92-94  8.5

Further polymers are (e.g. random) polymers derived from chitosan, basedon the following monomer units IX and X

It is also possible to use in the core material envelope substances orsubstance mixtures which, with regards to their solubility behaviour,react to a change in the ionic concentration, i.e. ionicconcentration-sensitive polymers. For this purpose it is e.g. possibleto use the partly hydrolyzed polyvinyl acetates (commercially availableunder the trade names Mowiol®-Clariant) described in EP 284 191 A2 andEP 284 334 A2, which reveal a corresponding ionic concentrationdependence in the presence of borates due to the complexing of theborates with polyols. Initial successful tests have been carried outwith Mowiol® 56-88.

Another ionic concentration-sensitive polymer is the polysaccharideK-carrageenan, which proved to be in screening process 3 (cf. example 2)a polymer whose solubility is dependent on the potassium ionconcentration in the surrounding medium. K-carrageenan is represented bythe following formula XI:

This polymer, called “polymer 4” was tested according to screeningprocess 3. 4 g of K-carrageenan were dissolved in 96 g of water. 10 g ofMowiol® 18-88 were dissolved in 90 g of water and both solutions weremixed. The resulting solution was used for forming films and performingtests in the manner described hereinbefore and the following resultswere obtained:

Detergent conc. Weight loss at 30° C. Weight loss at 60° C. pH-value [%][%]   4 g/l 0.5-3.0 11.0-12.0 0.02 g/l 24.5-25.0 78.0-85.0

The above list of compounds suitable for the envelope according to theinvention is obviously not exhaustive. Further polymers, which changetheir solubility by a modification of the pH-value or concentration inthe desired range are conceivable or can be developed and areconsequently covered by the protective scope of the present invention.It is inter alia possible to use for the envelope according to theinvention compounds which, with respect to their solubility behaviour,react to a change in the concentration of nonionic compounds in thesurrounding medium. The substances suitable for the envelope accordingto the invention are not limited to polymeric compounds, although suchcompounds are preferred.

With the aid of the aforementioned screening process or processes, whichare adapted to the measurement of an concentration sensitivity, furthercommercially available materials or those obtainable by easymodifications can be tested for their suitability in the presentinvention. The choice of such polymers is an easily solved problem forthe expert in view of the correspondingly clear aims and the indicatedscreening processes.

EXAMPLE 4 Production of a Particle According to the Invention

The different cores described in example 1 were used as a basis for theproduction of particles according to the invention. These cores wereindividually or in a plurality (FIG. 6) provided with an envelope in adevice for the application of a film coating of the type known in thepharmaceutical industry (e.g. obtainable from Lödiger, Hüttlin, GS, tadesty and Driam).

In the case where the core or cores have an ingredient revealing acertain incompatibility with the envelope material, prior to theapplication of said envelope the core or cores can be provided with aprotective coating. It is possible to use various prior art materialssuch as e.g. cellulose, cellulose oderivatives, polyvinyl alcohol,polyvinyl alcohol derivatives and mixtures thereof. Although notprescribed, when using the cores of example 1 such a protective coatingwas used in all cases and use was made in preferred manner of a 10 wt. %aqueous solution of a polyvinyl alcohol, e.g. the polyvinyl alcoholMowiol® 5-88 (Clariant). The quantity of the protective coating appliedcan be varied by the expert as a function of the core composition andcorrespondingly adapted initial tests have revealed good results with 3wt. % in case 1a, 2 wt. % in case 1b, 3 wt. % in case 1c and 4 wt. % incase 1d of the polymer (dry weight), i n each case based on the weightof the complete particle.

The concentration-sensitive envelope can be applied to the core or coresor the protective coating in any random quantity and thickness, providedthat it is ensured that the envelope Is sufficiently rapidly dissolvedor detached in the clear rinsing cycle to enable the substance containedtherein to evolve its action. In a preferred embodiment to the cores areapplied 1 to 10 wt. %, preferably 4 to 8 wt. % of theconcentration-sensitive enveloping material (dry weight), based on thetotal particle weight.

Preferably the size of the inventive particles should be such that theyare not or at least not significantly discharged from the dishwasherduring the pumping out processes following the main cleaning cycle orintermediate rinsing cycle. Generally a size of max diameter 1 cm isadequate. Larger or smaller dimensions can obviously be chosen, providedthat the appropriate operation overall is ensured.

For the further tests “polymer 1” of example 3 was used as the envelopeand applied as 10% solution of the polymer in 0.055 N aqueous HCl.

EXAMPLE 5 Production of a Two-layer Dishwashing Agent Tablet with ClearRinsing Agent Particles

A typical two-layer dishwashing agent tablet suitable for receiving aclear rinsing agent particle in the cavity formed therein in accordancewith the present invention, can be produced by moulding the pulverulentingredients in prior art machines and using operating parameters knownfrom the prior art. One possible tablet shape is a parallelepipedictablet formed from two substantially equally thick layers and in thelargest surface of each of these layers is formed a hemisphericalrecess, so that on joining together the two half-tablets a substantiallyspherical cavity is formed in the interior (cf. FIG. 2).

The composition of the dishwashing agent tablet is based on commerciallyavailable products. An exemplified composition can be gathered fromtable 2. It is obviously possible to use other compositions,particularly those optimized for supporting the compound surrounding thecore (e.g. in the provision of alkalinity).

TABLE 2 White layer Coloured layer 50% 50% Sodium perborate monohydrate18.00 Sodium tripolyphosphate 48.00 48.00 Sodium carbonate 24.00 32.00Polyethylene glycol 6000 3.00 5.00 Polymer 3.00 TAED 6.00 Enzyme 3.00Dye 0.02 Surfactant 4.50 2.50 Additive 2.50 0.50 100.00 100.00

For the tests performed in examples 6 and 7 half-tablets weighingapproximately 11.5 g were produced. The cavity resulting from thejoining of the half-tablets had an internal diameter of approximately1.2 cm.

The clear rinsing agent particle produced according to examples 1a and 4is placed in a hemispherical recess of the white or colouredhalf-tablet. Subsequently a fixing substance, e.g. an adhesive (e.g.polyethylene glycol, polyvinyl ether, polyvinyl alcohol, silicate,preferably melted PEG 4000) is applied to the corresponding half-tabletsurface and optionally the clear rinsing agent particle and the secondhalf-tablet (coloured or white) is pressed onto the first half-tabletwith clear rinsing agent particle.

EXAMPLE 6

This example describes a test proving the transfer of the clear rinsingagent surfactant into the clear rinsing cycle using the tablet producedaccording to example 5.

The clear rinsing agent particles have an average surfactant orpolyethylene glycol content of in each case approximately 0.37 g. Theaverage water quantity in the clear rinsing cycle is approximately 5litres. The expected maximum quantity of surfactant plus PEG in theclear rinsing cycle should therefore be 0.148 g/l when using one tabletper rinsing cycle.

In each case three different tests were performed with three differenttablets in a BOSCH SMS 3047 dishwasher. The water hardness wasapproximately 17° dH.

1. Dishwashing agent tablet without clear rinsing agent particles;temperature 65° C.

2. Dishwashing agent tablet with clear rinsing agent particles (example6); temperature 65° C.

3. Dishwashing agent tablet with clear rinsing agent particles (example6); temperature 55° C.

In each test a minimum of 1 litre of washing liquor was removed from theclear rinsing cycle shortly before the water was drained. The sampleswere designated 1.1 to 3.3. The liquor was then analyzed in order todetect the total quantity of surfactant plus polyethylene glycol in theclear rinsing cycle. The measurements were performed in that thesurfactant and PEG were extracted, the solvent evaporated and agravimetric determination of the nonvolatile residue was performed.

It is pointed out that with this analytical method both the nonionicsurfactant and the polyethylene glycol can be established.

TABLE 3 Test 1 (n = 1) Test 2 (n = 2) Test 3 (n = 3) mg/l % mg/l % mg/l% n.1 1.0 43.6 29.5 91.9 62.1 n.2 10.4 48.8 33.0 64.2 43.4 n.3 7.0 32.722.1 76.5 51.7

EXAMPLE 7

The test described in this example is used for testing the compositionaccording to the invention for effectiveness in the clear rinsing cycle.

For comparison with the inventively produced dishwashing agent tabletwith clear rinsing agent particles, as produced in example 6, the clearrinsing efficiency of separately added dishwashing agent and clearrinsing agent was investigated. The dishwashing agent corresponded tothe composition of the tablet according to the invention and acommercial clear rinsing agent was used. A BOSCH SMS 3047 dishwasher wasused. The water hardness was approximately 17 to 19° H. The temperaturewas 65° C. The dishwasher was loaded with 20 glasses, 20 black porcelainplates and 20 cutlery items.

The dirtying of the dishwasher load was carried out in the followingway. 50 g of minced meat (pork:beef 1:1) were roast with 2 g of fat.After reaching a slightly brownish colour, to the meat was added a gravycontaining 100 ml of water, 1 g of gravy binder and 2.5 g of instantgravy.

This material was added to the dishwasher, the screen being closed by aplug in order to have the dirtying action in the machine up to the endof the washing program. The dishwashing agent was fed in at the start ofthe clear rinsing cycle. The dishwasher load was evaluated 10 minutesafter the end of the dish rinsing cycle.

Visual evaluation was based on the following:

4 points=no marks

3 points=1 to 4 marks

2 points=more than 4 marks up to ¼ of the surface covered with marks

1 point=¼ to ¼ the surface covered with marks

0 point=almost completely covered with marks.

The mark or spot prevention efficiency is expressed as a percentage,100% efficiency representing the maximum number of 228 points. Theresults are given in table 4.

TABLE 4 Efficiency Cleaning agent + Cleaning agent + Tablet with clear 2ml of clear 3 ml of clear rinsing agent rinsing agent rinsing agentparticles Porcelain 66.9 75.6 96.9 Glass 25.6 26.9 49.4 Cutlery 80.690.6 78.8 Total 57.7 64.4 75.0

The results reveal an excellent clear rinsing agent of the compositionaccording to the invention. This was particularly marked with porcelainand glass, the efficiency in the case of table cutlery being comparablewith that of conventional compositions. Surprisingly there was in partsuperior clear rinsing efficiency of the inventive composition comparedwith the conventional procedure of separately adding dishwashing agentand clear rinsing agent.

The features of the invention disclosed in the above description, theclaims and the drawings can be essential to the implementation of theinvention in its different embodiments, both singly and in randomcombination.

What is claimed is:
 1. A composition for use in a dishwashing machine,comprising a tablet composition comprising an ionic compound whichdeploys its function in a main cleaning cycle of the dishwashingmachine, a particle having a core, the particle incorporating asubstance intended to perform its function during a rinsing cycle of thedishwashing machine, and an envelope surrounding the core, the envelopecomprising a compound whose solubility is inversely proportional to aconcentration of the ionic compound in a surrounding medium, wherein theparticle is arranged in or on the tablet such that only a portion of asurface of the particle directly contacts the tablet, wherein theconcentration of the ionic compound caused by dissolution of the tabletin the main cleaning cycle is sufficiently high to prevent dissolutionof the envelope or detachment of the envelope from the particle core. 2.The composition according to claim 1, in which the particle is coatedwith a substance which, independently of the concentration of the ioniccompound in the surrounding medium, dissolves or separates from theparticle during the main rinsing cycle of the dishwashing machine. 3.The composition according to claim 1, in which the particle is receivedin a cavity of the tablet wherein the cavity surrounds the particle. 4.The composition according to claim 3, in which the particle has a samevolume as the cavity.
 5. The composition according to claim 3, in whichthe cavity has a larger volume than the particle contained therein. 6.The composition according to claim 5, in which the particle is looselyarranged in an interior of the cavity.
 7. The composition according toclaim 5, in which the particle is fixed in an interior of the cavity. 8.The composition according to claim 7, in which the particle is fixed byan adhesive.
 9. The composition according to claim 3, in which thecavity is substantially centrally positioned in an interior of thetablet.
 10. The composition according to claim 9, in which the tablethas a single spherical cavity.
 11. The composition according to claim10, in which the cavity contains a single spherical particle whosediameter is less than an internal diameter of the cavity.
 12. Thecomposition according to claim 1, in which the particle is received in acavity of the tablet, wherein the cavity only partly surrounds theparticle.
 13. The composition according to claim 1, in which theparticle is received in a depression in a surface of the tablet.
 14. Thecomposition according to claim 12, in which the particle is placed inthe cavity in such a way that it does not project beyond the surface ofthe tablet.
 15. The composition according to claim 13, in which theparticle is placed in the depression in such a way that it does notproject beyond the surface of the tablet.
 16. The composition accordingto claim 14, in which the cavity contains a single particle, whosevolume equals that of the cavity.
 17. The composition according to claim16, in which the cavity has a circular mouth.
 18. The compositionaccording to claim 17, in which the mouth of the cavity is smaller thana diameter of the particle received therein.
 19. The compositionaccording to claim 18, in which the particle is loosely arranged in thecavity.
 20. The composition according to claim 18, in which the particleis fixed in the cavity.
 21. The composition according to claim 20, inwhich the particle is fixed by an adhesive.
 22. The compositionaccording to claim 1, in which the tablet comprises a compositionselected from the group consisting of a machine dishwashing agentcomposition, a water softener composition, a washing intensifiercomposition, and combinations thereof.
 23. The composition according toclaim 1, in which the envelope incorporates a compound which at theconcentration of the ionic compound, at the end of the main cleaningcycle of the dishwashing machine, is insoluble or only slightly solubleand, at a concentration of the ionic compound in the clear rinsingcycle, the envelope compound has an adequate solubility to ensure thatit is dissolved or detached from the core such that release of the corematerial into a medium of the clear rinsing cycle is possible.
 24. Thecomposition according to claim 23, in which a solubility of the envelopecompound is inversely proportional to OH-ionic concentration in thesurrounding medium.
 25. The composition according to claim 24, whereinat a pH-value above 10 the envelope compound has no or only a limitedsolubility and at a pH-value below 9 has a solubility such that itbecomes dissolved or detached from the particle core.
 26. Thecomposition according to claim 23, in which the envelope compoundcomprises a polymer.
 27. The composition according to claim 26, in whichthe envelope compound comprises a pH-sensitive polymer incorporating arepeat unit having a basic function which does not form part of abackbone chain of the polymer.
 28. The composition according to claim27, in which the repeat unit is based on a compound selected from thegroup consisting of vinyl alcohol derivatives, acrylates and alkylacrylates having the basic function.
 29. The composition according toclaim 27, in which the polymer is carbohydrate functionalized with thebasic function.
 30. The composition according to claim 27, in which thebasic function is an amine.
 31. The composition according to claim 30,in which the amine is a secondary or tertiary amine.
 32. The compositionaccording to claim 30, in which the repeat unit is based on a compoundof formula III:

in which G is a linking group selected from —COO—,—OCO—,—CONH—,—NHCO—,—NHCONH—,—NHCOO—,—OCONH—or—OCOO—, each R₁ is hydrogen oran alkyl group with 1 to 3 carbon atoms, each R₂ is hydrogen or an alkylgroup with 1 to 5 carbon atoms, and x is an integer from 1 to
 6. 33. Thecomposition according to claim 32, in which the repeat unit is based ona compound of formula IV:

in which R₁ hydrogen or an alkyl group with 1 to 3 carbon atoms, each R₂is hydrogen or an alkyl group 1 to 5 carbon atoms, and x is an integerfrom 1 to
 6. 34. The composition according to claim 27, in which thebasic function is an imine.
 35. The composition according claim 27, inwhich the basic function is a basic aromatic N-containing group.
 36. Thecomposition according to claim 35, in which the basic function is apyridine group.
 37. The composition according to claim 35, in which thebasic function is an imidazole group.
 38. The composition according toclaim 24, in which the polymer is derived from chitosan.
 39. Thecomposition according to claim 24, in which the composition incorporatesk-carrageenan.
 40. The composition according to claim 1, in which thecore incorporates a material selected from the group consisting ofsurfactants, antibacterial compositions, silver protection agents,fragrances, bleaches, disinfectants, odor masking agents, anti-coatingagents, enzymes, and combinations thereof.
 41. The composition accordingto claim 40, in which the core is in a form of an encapsulated liquid.42. The composition according to claim 41, in which the encapsulatedliquid is contained in a gelatin capsule.
 43. The composition accordingto claim 40, in which the core is in solid form.
 44. The compositionaccording to claim 1, in which the core has a melting point higher than35° C.
 45. The composition according to claim 44, in which the core hasa melting point between 55° C. and 70° C.
 46. A process for washingdishes in a dishwashing machine, which comprises introducing into thedishwashing machine a composition comprising a tablet compositioncomprising an ionic compound which deploys its function in a maincleaning cycle of the dishwashing machine, a particle having a core, theparticle incorporating a substance intended to perform its functionduring a cycle of the dishwashing machine, and an envelope surroundingthe core, the envelope comprising a compound whose solubility isinversely proportional to a concentration of the ionic compound in asurrounding medium, wherein the particle is arranged in or on the tabletsuch that only a portion of a surface of the particle directly contactsthe tablet, wherein the concentration of the ionic compound caused bydissolution of the tablet in the main cleaning cycle is sufficientlyhigh to prevent dissolution of the envelope or detachment of theenvelope from the particle core.
 47. The process according to claim 46,comprising an additional step of introducing an additional dishwashingagent into said dishwashing machine.